Topic: 3DFACE hidden sides

[TopoWAR]

I could not, I have hours with this problem, a lisp that tells me which side of 3DFACE are visible or hidden,
thanks

[efernal]

(70 . 0) all visibles
(70 . 1) first hidden
(70 . 2) second hidden
etc...

[TopoWAR]

efernal , not, is the sum of the values, I do not know how to do the lisp.
I want a function that returns only the visible side, I hope someone help me

[Lee Mac]

DXF 70 is bit-coded, demo:

Code - Auto/Visual Lisp: [Select]

1. (defun _HiddenEdges ( 3DFaceEntity )
2.     (
3.         (lambda ( x )
4.             (apply 'append
5.                 (mapcar
6.                     (function
7.                         (lambda ( b )
8.                             (if (< 0 (logand (car b) x)) (cdr b))
9.                         )
10.                     )
11.                    '(
12.                         (1 "1st edge is invisible")
13.                         (2 "2nd edge is invisible")
14.                         (4 "3rd edge is invisible")
15.                         (8 "4th edge is invisible")
16.                     )
17.                 )
18.             )
19.         )
20.         (cdr (assoc 70 (entget 3DFaceEntity)))
21.     )
22. )

Code - Auto/Visual Lisp: [Select]

1. (_HiddenEdges (car (entsel)))

[TopoWAR]

Lee Mac , you are great teacher

[Lee Mac]

Thank you TopoWAR, happy coding!